Stocks dropped for a second day as a reduction in Greece’s debt rating and a $3.65 billion loss by a Dubai developer added to concern that global credit markets are struggling to recover.

Commodities led the decline as the US dollar strengthened, pushing oil to an eight-week low and capping the steepest three-day drop for gold in more than a year. Gold for February delivery tumbled 1.8 percent to $1,143.40 an ounce and the most-active contract slid 6.1 percent over the past three sessions.

The S&P 500 lost 1 percent to 1,091.94. The Dow Jones industrial average tumbled 104.14 points, or 1 percent, to 10,285.97 and the Nasdaq dropped 16.62, or 0.76 percent, to 2,172.99.